This invention relates to an occlusion device for the closure of physical apertures, such as vascular or septal apertures. More specifically, this invention relates to an occlusion device for closing an aperture that is capable of self-centering in the aperture.
The heart is generally comprised of four chambers: the left and right atrium, and the left and right ventricle. Separating the left and right sides of the heart are two walls, or septa. The wall between the two atria is the interatrial septum and the wall between the two ventricles is the interventricular septum. There are several defects which can affect the septa of both children and adults, including patent ductus arteriosus, patent foramen ovale, atrial septal defects (ASDs), and ventricular septal defects (VSDs). Although the causes and physical aspects of these defects vary by type, each of these defects is generally an aperture, flap, or hole in the septum that allows blood to shunt between chambers in the heart where there is no blood flow in a normal, healthy heart. This abnormal shunt can cause a variety of health problems.
Normally, permanently repairing certain cardiac defects in adults and children requires open heart surgery, which is a risky, painful, and expensive procedure. Surgically closing an aperture in the heart requires the patient to undergo general anesthesia and requires opening of the chest cavity. The patient may spend several days in the hospital and thereafter may take several weeks to recover before being able to return to normal levels of activity.
To avoid the risks and discomfort associated with open heart surgery, modern occlusion devices have been developed that are small, implantable devices capable of being delivered to the heart through a catheter. These devices are used to close the aperture, but do not require surgery. Rather than surgery, a catheter inserted into a major blood vessel, and an occlusion device is moved through the catheter to the treatment site, where it can then be deployed at the defect. This procedure can be performed in a cardiac cathlab, and reduces the risks, pain, and long recovery time associated with open heart surgery.
There are currently several types of occlusion devices capable of being inserted via a catheter including button devices, collapsible umbrella-like structures, and plug-like devices. These modern occlusion devices can repair a wide range of cardiac defects, including patent foramen ovale, patent ductus arteriosus, atrial septal defects, ventricular septal defects, and may occlude other cardiac and non-cardiac apertures.
One form of occlusion device generally has a first side, a second side, and a center section. Once the occluder is deployed, the first side is positioned on one side of the aperture to be occluded, and the second side is positioned on the other side of the aperture. The occluder's center section extends through the center of the defect or aperture being occluded. The first and second sides of the occlusion device serve to occlude the aperture on the respective sides of the aperture. Because the center section of the occlusion device may be small relative to the size of the aperture to be occluded, it is a challenge to ensure the occlusion device is properly centered across the aperture.
As mentioned, several types of septal defects exist. In addition, the size and shape of each defect and the size and shape of the heart varies from patient to patient. It is important that any occlusion device be properly centered in the defect so that the device is most effective at sealing the aperture. This is particularly true for larger defects. As such, it is important for the occlusion device to be centered in the defect to ensure the left and right sides of the device properly cover the aperture. If the defect is not properly occluded, blood will continue to shunt through the defect, which lessens the effectiveness of the device.
It is also important to reduce the overall bulk of the occlusion device as much as possible, while still retaining its ability to properly occlude the aperture or defect. This is essential for the treatment of children because they have smaller vessels than adults. The occlusion device must collapse down to a very small diameter, so it will fit in a catheter narrow enough to thread though a child's tiny vessels. It is also desirable that the occlusion device maintain a low profile after placed at the site of the defect, in order to minimize corrosion of the metal and potential blood clots.
Thus, there is a need in the art for an occlusion device which has a centering system to improve the ability of the device to be centered in the defect, while also having the ability to collapse to a small diameter and maintain a low profile against the septum.